No, you cannot open Paypal pages in new windows or tabs or even display in an iframe. It’s a security thing with Paypal. I’m not sure how they prevent it, but I tried everything I could think of a couple of years ago to do just that and finally contacted them. They said it was not possible because it would make it easy for people to do some sneaky stuff, redirecting and such, if it could open in a new window (paraphrasing).